title: Effect of admission time on mortality in an intensive care unit in Mainland China: a propensity score matching analysis.
abstract: BACKGROUND
  The relationship between admission time and intensive care unit (ICU) mortality is inconclusive and influenced by various factors. This study aims to estimate the effect of admission time on ICU outcomes in a tertiary teaching hospital in China by propensity score matching (PSM) and stratified analysis.
  
  
  METHODS
  A total of 2,891 consecutive patients were enrolled in this study from 1 January 2009 to 29 December 2011. Multivariate logistic regression and survival analysis were performed in this retrospective study. PSM and stratified analysis were applied for confounding factors, such as Acute Physiology and Chronic Health Evaluation II (APACHE II) score and admission types.
  
  
  RESULTS
  Compared with office hour subgroup (n = 2,716), nighttime (NT, n = 175) subgroup had higher APACHE II scores (14 vs. 8, P < 0.001), prolonged length of stay in the ICU (42 vs. 24 h, P = 0.011), and higher percentages of medical (8.6% vs. 3.3%, P < 0.001) and emergency (59.4% vs. 12.2%, P < 0.001) patients. Moreover, NT admissions were related to higher ICU mortality [odds ratio (OR), 1.725 (95% CI 1.118-2.744), P = 0.01] and elevated mortality risk at 28 days [14.3% vs. 3.2%; OR, 1.920 (95% CI 1.171-3.150), P = 0.01]. PSM showed that admission time remained related to ICU outcome (P = 0.045) and mortality risk at 28 days [OR, 2.187 (95% CI 1.119-4.271), P = 0.022]. However, no mortality difference was found between weekend and workday admissions (P = 0.849), even if weekend admissions were more related to higher APACHE II scores compared with workday admissions.
  
  
  CONCLUSIONS
  NT admission was associated with poor ICU outcomes. This finding may be related to shortage of onsite intensivists and qualified residents during NT. The current staffing model and training system should be improved in the future.
authors.forename: Min-Jie
authors.initials: MJ
authors.lastname: Ju
authors.forename: Guo-Wei
authors.initials: GW
authors.lastname: Tu
authors.forename: Yan
authors.initials: Y
authors.lastname: Han
authors.forename: Hong-Yu
authors.initials: HY
authors.lastname: He
authors.forename: Yi-Zhou
authors.initials: YZ
authors.lastname: He
authors.forename: Hai-Lei
authors.initials: HL
authors.lastname: Mao
authors.forename: Zhao-Guang
authors.initials: ZG
authors.lastname: Wu
authors.forename: Yi-Qing
authors.initials: YQ
authors.lastname: Yin
authors.forename: Jian-Feng
authors.initials: JF
authors.lastname: Luo
authors.forename: Du-Ming
authors.initials: DM
authors.lastname: Zhu
authors.forename: Zhe
authors.initials: Z
authors.lastname: Luo
authors.forename: Zhang-Gang
authors.initials: ZG
authors.lastname: Xue
mesh_terms: D018806:APACHE; D000368:Aged; D002681:China / Q000453:epidemiology; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D010343:Patient Admission / Q000706:statistics & numerical data*; D057216:Propensity Score